1. Field of the Invention
The present invention relates to a combustion turbine power generating system that can realize high efficient and high reliable operation and method of controlling the same.
2. Description of Related Art
As disclosed in JP-A-09-289776, in a case of a conventional combustion turbine power generating system, a command value for number of revolutions is calculated from a load power to be outputted and the command value for the number of revolutions is inputted to a turbine controller to control the number of revolutions for a combustion turbine, thereby controlling the number of revolutions for a power generator.
In the above technique, the command value for the number of revolutions is calculated from the output power of the turbine on the basis of the knowledge that the output power of the turbine is proportional to its the number of revolutions.
The turbine controller adjusts a quantity of fuel to be fed on the basis of the command value for the number of revolutions calculated as above and controls the number of revolutions. However, since the efficiency of turbine is influenced by a temperature of suction air or the like, the turbine cannot be always operated at the number of revolutions that the highest efficiency and a low Nox (nitrogen oxide) are attained for a certain fuel quantity. Accordingly, it is difficult that the efficiency of the turbine is always kept to be high.
It is an object of the present invention to make power generation at high efficient state of turbine by controlling the number of revolutions of a power generator.
According to an aspect of the present invention, in a combustion turbine power generating system for supplying an output of turbine to an electric power system through a power generator and a power converter capable of converting the power between AC current and DC current, the speed of power generator is always controlled by means of the power converter connected to the power generator.
Further, an optimum speed command is produced from state quantity of the turbine and the speed of power generator is controlled on the basis of the optimum speed command by means of the power converter connected to the power generator.
Moreover, when a fuel quantity is varied by adjustment of fuel or the like and a current of the power generator is greater than a predetermined value, the speed of power generator is increased temporarily.